Cognitive dysfunction is one of the leading causes of disability in multiple scelerosis (MS), exacting a tremendous socioeconomic and interpersonal toll. Unfortunately, previous attempts to rehabilitate cognitive dysfunction in MS have had only limited success. The investigators intend to overcome the limitations of previous studies by: 1) testing the efficacy of interventions that specifically target cognitive functioning; and 2) utilizing a novel outcome measurement that may be more sensitive and ecologically valid for the cognitive dysfunction that occurs in MS. The proposed experiments will determine the efficacy of donepezil therapy and glucose administration for enhancing memory functioning in individuals with MS. The investigators will also measure secondary outcomes assessing other areas of cognitive dysfunction (i.e., nonverbal memory, conceptual thinking, processing speed) which may improve with intervention.